Link adaptation for mobile communication networks is used to control an audio codec mode having variable bitrate properties based on the quality of wireless channels. A channel quality indicator (CQI), which is a measurement of the communication quality of wireless channels, may be defined as a carrier-to-interferer ratio (CIR). Since, in most codec mode control methods for mobile communication networks, the quality of transfer of packets via the internet is not considered, it is difficult to provide high quality of service (QoS) multimedia services in mobile environments such as a convergence internet protocol (IP) network where the transfer performance of packets are highly variable.